While the heat such as that evolved by a cost-effective optimized-efficiency diesel engine may be very low on the cylinder crankshaft housing, this circumstance is not the case for “hot zones” at manifolds, turbochargers, catalytic converters, etc. As a result of the increasingly compact design of the engines, components that are not thermally “compatible” are coming to be in ever closer proximity. The use of shielding components such as heat shields is needed to protect adjacent heat-sensitive assemblies such as sensors, fuel lines, barometric cells, body parts, and so forth from heat-generating engine components. The situation is intensified by the compact design in that the high assembly packing density narrows the cooling air stream. Noise abatement measures may also contribute to the problem. For example, plastic floor plates having the function of reducing the level of sound escaping from the engine compartment to the roadway may possibly cause effective insulation whereby heat is trapped in the engine compartment. Because of their high surface temperature in some phases, catalytic converters are among the sources of heat necessitating use of protective shield barriers. A typical example is that of design measures such as positioning the catalytic converter in the immediate vicinity of the manifold. This design principle, serving the purpose of rapid heating of the catalytic converter and thereby of reducing emissions during the cold start phase, transfers a strong heat source into the engine compartment, where a considerable number of assemblies are crowded into restricted space. Another reason for the increasing importance of shielding components such as heat shields is the trend toward use of thermoplastics. These outstandingly moldable, light, and economically efficient materials are employed with increasing frequency in the engine compartment, but require special attention in view of the ambient temperatures generated at the site of application in connection with other heat-generating engine parts (New Materials and Development Tools for Protection from Heat in MTZ 12/2001, Vol. 62, page 1044 et seq.)
DE 102 47 641 B3 discloses a generic structural component, in particular one in the form of a sound-damping shielding component, as a structural element of a motor vehicle. In this disclosed solution, to improve sound damping the shielding component includes a shielding body having a base edge as structural element of a first type. The body may be fastened on the edge side by angular U-shaped elements inside the engine compartment to stationary elements mounted in that compartment, and shields heat-generating engine components from heat-sensitive structural components.
The shielding body as structural element is a U-shaped arch in a central area, and is configured to be symmetrical for this purpose. The U-shaped central area undergoes transition on the edge side to edge areas of more pronounced curvature. The U-shaped arches on the two edge areas opposite each other are subsequently mounted as fastening means. The shielding body has two sheet metal layers between which extends a sound-absorbing and/or heat-insulating layer. A border in which the flanged edge of one cover layer covers the edge area of the other cover layer is used for fastening the metal cover layers to each other. To save weight, the shielding body may be made of aluminum or another light metal.
The disclosed solution is applied by preference to shield a coupling between a drive flange and a drive shaft from the sound of the body coming from the gearing and to avoid a long-term effect through thermal radiation of an adjacent exhaust gas pipe. Experiments were conducted in which the sound emission was reduced by 3 dB in the disclosed solution. If in the disclosed solution maintenance or repair work on the coupling or the drive shaft becomes necessary, the shield component normally must be disassembled. The disassembly requires separating the shielding body by loosening a connection unit in the form of screws from the angular U-shaped elements as fastening means. This disassembly is time-consuming and consequently increases maintenance and repair costs. If it is desired only to inspect the shielded components in the context of maintenance, complete disassembly of the shielding body on the engine structural components or body parts is normally also necessary, depending on the installation conditions.
Spring clips have in fact also been described in the state of the art as being used to connect shielding components detachably to each other or to fasten such clips reversibly on engine structural components or body parts of a vehicle to eliminate the time-consuming screw connection process. However, those spring clips are often complicated and expensive to produce and, especially in disassembly of such shielding components, expand together with their shackles so that the elastic effect is largely lost. The elastic effect loss results in the spring clips becoming unusable for a new fastening process. In addition, as additional assembly elements they must be handled and stored.